need help with translation of a word (construction term)

I need the translation for the construction word "Waterstop". A waterstop is used a cemented joint to prevent water from leaking up or down the joint. The waterstop is usually dumbell in shape and made of PVC. ( Poly Vinyl plastic)

Thanks!
Monica

Normalmente entre las juntas de dilatación de un edificio que se encuentre sometido a humedades exteriores se pone una material impermabilizante, ya sea resinas (epoxi) o tela asfaltica para evitar que transmita esa humedad exterior al interior del edificio ya que el hormigón es permeable.

Waterstop = material impermeabilizante (sea cual sea).

V.Turu

I am not sure about the dumbell shape of a waterstop. For sure a waterstop material is "impermeabilizante" but with such shape...????:confused: can you offer, if needed of course, more context? Maybe impermeabilizante will do, but what does not seem to fit is the dumbell shape.